If it is minification, then you already have a tool that process the code. The tool can easily just add the missing colon before concatenation.
Here's a very lengthy discussion on how the very popular minifier UglifyJS (version 1) originally removed trailing semicolons, causing this exact problem: https://web.archive.org/web/20130319222210/https://github.co...
In the real world, it's irrelevant what tools could be reasonably expected to do. What matters is what they actually do. Expecting your tools to insert semicolons for you is the path that leads to peril.